Hypothesis Testing

Suppose that X1,...Xn form a random sample from a uniform distribution on the interval [0,theta], and that the following hypothesis are to be tested:
null: theta greater than or equal to 2
alternative: theta less than 2
Let Yn=max(X1,...Xn) and consider a test procedure such that the critical region contains all the outcomes for which Yn is greater than or equal to 1.5

Determine the power function of the test
Determine the size of the test